In downhole drilling, such as oil and gas drilling, often sinter polycrystalline diamond is incorporated into the bits. The diamond is supported by a carbide substrate typically brazed within pockets formed in the bits.
U.S. Pat. No. 5,533,582 to Tibbitts, which is herein incorporated by reference for all that it contains, discloses a full cutting element including a substantially cylindrical backing and cutter mounted thereon is cut generally along the length thereof to produce a pair of semicylindrical partial cutting elements. In the case of an unused cutting element, each partial cutting element is mounted on a different semicylindrical tungsten carbide base to produce a substantially cylindrical unit which is mounted on a bit using a low temperature braze. In the case of a used full cutting element, the cutting element is cut to separate the worn portion from the remainder of the bit and only the unused portion is used to form a cylindrical unit with a corresponding semicylindrical tungsten carbide base. In another aspect, a partial cutting element is received in a pocket formed on a bit body. The pocket includes a pair of opposed side surfaces which substantially flushly abut the curved surfaces of the backing on the partial cutter.
U.S. Pat. No. 4,254,840 to Shay, Jr., which is herein incorporated by reference for all that it contains, discloses a protruding insert for use in an oil well drill bit is disclosed which insert is made of a hard metal substance and utilizes a tangential spherical surface having opposed flattened sides.
U.S. Pat. No. 4,597,456 to Ecer, which is herein incorporated by reference for all that it contains, discloses a roller bit cutter comprising a tough, metallic generally conical and fracture resistant core having a hollow interior, the core defining an axis, an annular metallic radial bearing layer carried by said core at the interior thereof to support the core for rotation, said bearing layer extending about said axis, an impact and wear resistant metallic inner layer on the core, at the interior thereof, to provide an axial thrust bearing, and hard metallic inserts having anchor portions carried by the core and partly embedded therein, the inserts protruding outwardly at the exterior of the core to define cutters, at least some of the inserts spaced about said axis, and a wear resistant outer metallic layer on the exterior of said core.
U.S. Pat. No. 5,348,109 to Griffin, which is herein incorporated by reference for all that it contains, discloses a cutter assembly for a rotary drill bit comprising a preform cutting element mounted on a carrier. The cutting element includes a thin cutting table of polycrystalline diamond, defining a front cutting face and a cutting edge bonded to a less hard substrate which is in turn bonded to the carrier. The substrate which is in turn bonded to the carrier. The substrate and/or the carrier comprises a first portion of high erosion resistance, formed for example from tungsten carbide, and a second portion of lower erosion resistance, formed for example from tungsten metal, which is located in the vicinity of the cutting edge of the cutting element so that, in use, the wear flat is mostly formed in the material of lower erosion resistance.